In a small bowl, mix the fromage blanc with the horseradish, mustard, tarragon and chives; season with salt and pepper.

On a work surface, arrange 2 roast beef slices, overlapping the long ends, and spread with one-fourth of the fromage blanc mixture. Lay one pickle quarter at a short end and roll the roast beef around the pickle into a tight cylinder. Repeat with the remaining roast beef, fromage blanc mixture and pickle quarters. Trim the edges of each roll and slice them 1 inch thick. Arrange on a platter and serve.